计算距离A的给定距离的A-B线上的点
我很疯狂地计算沿着给定线A-B的点，在距离A的给定距离处，以便我可以“绘制”两个给定点之间的线。一开始听起来很简单，但我似乎无法做到这一点。更糟糕的是，我不明白我哪里出错了。几何（和一般的数学）不是我强大的套件。
我已经阅读了类似的问题，并在那里有答案。事实上，我直接从 Mads Elvheim 的回答中解除了我对CalculatePoint函数的当前实现：Given a start and end point, and a distance, calculate a point along a line（如果我理解正确的话，在后面的评论中加上更正）因为我的独立尝试解决这个问题让我无处可去，除了一流的快车票frusterpationland。
这是我的更新代码（请参阅EDIT备注帖子的底部）：
using System;
using System.Drawing;
using System.Windows.Forms;
namespace DrawLines
{
public class MainForm : Form
{
// =====================================================================
// Here's the part I'm having trouble with. I don't really understand
// how this is suposed to work, so I can't seem to get it right!
// ---------------------------------------------------------------------
// A "local indirector" - Just so I don't have go down and edit the
// actual call everytime this bluddy thing changes names.
private Point CalculatePoint(Point a, Point b, int distance) {
return CalculatePoint_ByAgentFire(a, b, distance);
}
#region CalculatePoint_ByAgentFire
//AgentFire: Better approach (you can rename the struct if you need):
struct Vector2
{
public readonly double X;
public readonly double Y;
public Vector2(double x, double y) {
this.X = x;
this.Y = y;
}
public static Vector2 operator -(Vector2 a, Vector2 b) {
return new Vector2(b.X - a.X, b.Y - a.Y);
}
public static Vector2 operator *(Vector2 a, double d) {
return new Vector2(a.X * d, a.Y * d);
}
public override string ToString() {
return string.Format("[{0}, {1}]", X, Y);
}
}
// For getting the midpoint you just need to do the (a - b) * d action:
//static void Main(string[] args)
//{
// Vector2 a = new Vector2(1, 1);
// Vector2 b = new Vector2(3, 1);
// float distance = 0.5f; // From 0.0 to 1.0.
// Vector2 c = (a - b) * distance;
// Console.WriteLine(c);
//}
private Point CalculatePoint_ByAgentFire(Point a, Point b, int distance) {
var vA = new Vector2(a.X, a.Y);
var vB = new Vector2(b.X, b.Y);
double lengthOfHypotenuse = LengthOfHypotenuseAsDouble(a,b);
double portionOfDistanceFromAtoB = distance / lengthOfHypotenuse;
var vC = (vA - vB) * portionOfDistanceFromAtoB;
Console.WriteLine("vC="+vC);
return new Point((int)(vC.X+0.5), (int)(vC.Y+0.5));
}
// Returns the length of the hypotenuse rounded to an integer, using
// Pythagoras' Theorem for right angle triangles: The length of the
// hypotenuse equals the sum of the square of the other two sides.
// Ergo: h = Sqrt(a*a + b*b)
private double LengthOfHypotenuseAsDouble(Point a, Point b) {
double aSq = Math.Pow(Math.Abs(a.X - b.X), 2); // horizontal length squared
double bSq = Math.Pow(Math.Abs(b.Y - b.Y), 2); // vertical length squared
return Math.Sqrt(aSq + bSq); // length of the hypotenuse
}
#endregion
//dbaseman: I thought something looked strange about the formula ... the question
//you linked was how to get the point at a distance after B, whereas you want the
//distance after A. This should give you the right answer, the start point plus
//distance in the vector direction.
//
// Didn't work as per: http://s1264.photobucket.com/albums/jj496/corlettk/?action=view¤t=DrawLinesAB-broken_zps069161e9.jpg
//
private Point CalculatePoint_ByDbaseman(Point a, Point b, int distance) {
// a. calculate the vector from a to b:
double vectorX = b.X - a.X;
double vectorY = b.Y - a.Y;
// b. calculate the length:
double magnitude = Math.Sqrt(vectorX * vectorX + vectorY * vectorY);
// c. normalize the vector to unit length:
vectorX /= magnitude;
vectorY /= magnitude;
// d. calculate and Draw the new vector, which is x1y1 + vxvy * (mag + distance).
return new Point(
(int)((double)a.X + vectorX * distance) // x = col
, (int)((double)a.Y + vectorY * distance) // y = row
);
}
// MBo: Try to remove 'magnitude' term in the parentheses both for X and for Y expressions.
//
// Didn't work as per: http://s1264.photobucket.com/albums/jj496/corlettk/?action=view¤t=DrawLinesAB-broken_zps069161e9.jpg
//
//private Point CalculatePoint_ByMBo(Point a, Point b, int distance) {
// // a. calculate the vector from a to b:
// double vectorX = b.X - a.X;
// double vectorY = b.Y - a.Y;
// // b. calculate the length:
// double magnitude = Math.Sqrt(vectorX * vectorX + vectorY * vectorY);
// // c. normalize the vector to unit length:
// vectorX /= magnitude;
// vectorY /= magnitude;
// // d. calculate and Draw the new vector, which is x1y1 + vxvy * (mag + distance).
// return new Point(
// (int)( ((double)a.X + vectorX * distance) + 0.5 )
// , (int)( ((double)a.X + vectorX * distance) + 0.5 )
// );
//}
// Didn't work
//private Point CalculatePoint_ByUser1556110(Point a, Point b, int distance) {
// Double magnitude = Math.Sqrt(Math.Pow(b.Y - a.Y, 2) + Math.Pow(b.X - a.X, 2));
// return new Point(
// (int)(a.X + distance * (b.X - a.X) / magnitude + 0.5)
// , (int)(a.Y + distance * (b.Y - a.Y) / magnitude + 0.5)
// );
//}
// didn't work
//private static Point CalculatePoint_ByCadairIdris(Point a, Point b, int distance) {
// // a. calculate the vector from a to b:
// double vectorX = b.X - a.X;
// double vectorY = b.Y - a.Y;
// // b. calculate the proportion of hypotenuse
// double factor = distance / Math.Sqrt(vectorX*vectorX + vectorY*vectorY);
// // c. factor the lengths
// vectorX *= factor;
// vectorY *= factor;
// // d. calculate and Draw the new vector,
// return new Point((int)(a.X + vectorX), (int)(a.Y + vectorY));
//}
// Returns a point along the line A-B at the given distance from A
// based on Mads Elvheim's answer to:
// https://stackoverflow.com/questions/1800138/given-a-start-and-end-point-and-a-distance-calculate-a-point-along-a-line
private Point MyCalculatePoint(Point a, Point b, int distance) {
// a. calculate the vector from o to g:
double vectorX = b.X - a.X;
double vectorY = b.Y - a.Y;
// b. calculate the length:
double magnitude = Math.Sqrt(vectorX * vectorX + vectorY * vectorY);
// c. normalize the vector to unit length:
vectorX /= magnitude;
vectorY /= magnitude;
// d. calculate and Draw the new vector, which is x1y1 + vxvy * (mag + distance).
return new Point(
(int)(((double)a.X + vectorX * (magnitude + distance)) + 0.5) // x = col
, (int)(((double)a.Y + vectorY * (magnitude + distance)) + 0.5) // y = row
);
}
// =====================================================================
private const int CELL_SIZE = 4; // width and height of each "cell" in the bitmap.
private readonly Bitmap _bitmap; // to draw on (displayed in picBox1).
private readonly Graphics _graphics; // to draw with.
// actual points on _theLineString are painted red.
private static readonly SolidBrush _thePointBrush = new SolidBrush(Color.Red);
// ... and are labeled in Red, Courier New, 12 point, Bold
private static readonly SolidBrush _theLabelBrush = new SolidBrush(Color.Red);
private static readonly Font _theLabelFont = new Font("Courier New", 12, FontStyle.Bold);
// the interveening calculated cells on the lines between actaul points are painted Black.
private static readonly SolidBrush _theLineBrush = new SolidBrush(Color.Black);
// the points in my line-string.
private static readonly Point[] _theLineString = new Point[] {
// x, y
new Point(170, 85), // A
new Point( 85, 70), // B
//new Point(209, 66), // C
//new Point( 98, 120), // D
//new Point(158, 19), // E
//new Point( 2, 61), // F
//new Point( 42, 177), // G
//new Point(191, 146), // H
//new Point( 25, 128), // I
//new Point( 95, 24) // J
};
public MainForm() {
InitializeComponent();
// initialise "the graphics system".
_bitmap = new Bitmap(picBox1.Width, picBox1.Height);
_graphics = Graphics.FromImage(_bitmap);
picBox1.Image = _bitmap;
}
#region actual drawing on the Grpahics
private void DrawCell(int x, int y, Brush brush) {
_graphics.FillRectangle(
brush
, x * CELL_SIZE, y * CELL_SIZE // x, y
, CELL_SIZE, CELL_SIZE // width, heigth
);
}
private void DrawLabel(int x, int y, char c) {
string s = c.ToString();
_graphics.DrawString(
s, _theLabelFont, _theLabelBrush
, x * CELL_SIZE + 5 // x
, y * CELL_SIZE - 8 // y
);
}
// ... there should be no mention of _graphics or CELL_SIZE below here ...
#endregion
#region draw points on form load
private void MainForm_Load(object sender, EventArgs e) {
DrawPoints();
}
// draws and labels each point in _theLineString
private void DrawPoints() {
char c = 'A'; // label text, as a char so we can increment it for each point.
foreach ( Point p in _theLineString ) {
DrawCell(p.X, p.Y, _thePointBrush);
DrawLabel(p.X, p.Y, c++);
}
}
#endregion
#region DrawLines on button click
private void btnDrawLines_Click(object sender, EventArgs e) {
DrawLinesBetweenPointsInTheString();
}
// Draws "the lines" between the points in _theLineString.
private void DrawLinesBetweenPointsInTheString() {
int n = _theLineString.Length - 1; // one less line-segment than points
for ( int i = 0; i < n; ++i )
Draw(_theLineString[i], _theLineString[i + 1]);
picBox1.Invalidate(); // tell the graphics system that the picture box needs to be repainted.
}
// Draws all the cells along the line from Point "a" to Point "b".
private void Draw(Point a, Point b) {
int maxDistance = LengthOfHypotenuse(a, b);
for ( int distance = 1; distance < maxDistance; ++distance ) {
var point = CalculatePoint(a, b, distance);
DrawCell(point.X, point.X, _theLineBrush);
}
}
// Returns the length of the hypotenuse rounded to an integer, using
// Pythagoras' Theorem for right angle triangles: The length of the
// hypotenuse equals the sum of the square of the other two sides.
// Ergo: h = Sqrt(a*a + b*b)
private int LengthOfHypotenuse(Point a, Point b) {
double aSq = Math.Pow(Math.Abs(a.X - b.X), 2); // horizontal length squared
double bSq = Math.Pow(Math.Abs(b.Y - b.Y), 2); // vertical length squared
return (int)(Math.Sqrt(aSq + bSq) + 0.5); // length of the hypotenuse
}
#endregion
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent() {
this.picBox1 = new System.Windows.Forms.PictureBox();
this.btnDrawLines = new System.Windows.Forms.Button();
((System.ComponentModel.ISupportInitialize)(this.picBox1)).BeginInit();
this.SuspendLayout();
//
// picBox1
//
this.picBox1.Dock = System.Windows.Forms.DockStyle.Fill;
this.picBox1.Location = new System.Drawing.Point(0, 0);
this.picBox1.Name = "picBox1";
this.picBox1.Size = new System.Drawing.Size(1000, 719);
this.picBox1.TabIndex = 0;
this.picBox1.TabStop = false;
//
// btnDrawLines
//
this.btnDrawLines.Location = new System.Drawing.Point(23, 24);
this.btnDrawLines.Name = "btnDrawLines";
this.btnDrawLines.Size = new System.Drawing.Size(77, 23);
this.btnDrawLines.TabIndex = 1;
this.btnDrawLines.Text = "Draw Lines";
this.btnDrawLines.UseVisualStyleBackColor = true;
this.btnDrawLines.Click += new System.EventHandler(this.btnDrawLines_Click);
//
// MainForm
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(1000, 719);
this.Controls.Add(this.btnDrawLines);
this.Controls.Add(this.picBox1);
this.Location = new System.Drawing.Point(10, 10);
this.MinimumSize = new System.Drawing.Size(1016, 755);
this.Name = "MainForm";
this.SizeGripStyle = System.Windows.Forms.SizeGripStyle.Hide;
this.StartPosition = System.Windows.Forms.FormStartPosition.Manual;
this.Text = "Draw Lines on a Matrix.";
this.Load += new System.EventHandler(this.MainForm_Load);
((System.ComponentModel.ISupportInitialize)(this.picBox1)).EndInit();
this.ResumeLayout(false);
}
private System.Windows.Forms.PictureBox picBox1;
private System.Windows.Forms.Button btnDrawLines;
#endregion
}
}
很抱歉，如果它有点长，但这是SSCCE从我的真实项目中挖掘出来的，这是A* shortest route algorithm的一个实现来运行MazeOfBolton ...即迷宫转轮。
我真正想要做的是预先计算迷宫（矩阵）中两个给定点（原点和目标）周围的“围栏”（即缓冲的MBR），以便“围栏”距离“两点之间的直线”给定距离，以便快速消除远离目标的数十万条可能的路径。
请注意，此编程挑战在几年前已经结束，因此这里的“竞争性plagerism”没有问题。不，这不是功课，事实上我是一名专业的程序员......我只是在这里度过了我的舒适区，即使是相对简单的几何形状。叹息。
所以...请有人能给我任何指示，以帮助我将CalculatePoint函数设置为正确：计算距离A的给定距离的AB线上的点吗？
提前感谢您的慷慨......即使是在阅读这篇文章的时候。
干杯。基思。
编辑：我刚刚更新了发布的源代码：
（1）我刚才意识到它不是自包含的。我忘记了单独的MainForm。 Designer .cs文件，我已将其附加到已发布代码的底部。
（2）最新版本包括我到目前为止所尝试的内容，并附有一张照片，链接到每张故障的图片......并且它们都是一样的。伊？ WTF？
我想我的问题可能在其他地方，就像其他人之前错过的一些时髦的窗体设置因为我忘了发布设计师生成的代码...除了everythingelse（在我的实际项目中）描绘我所期望的确切位置它，为什么计算点应该是不同的。我不知道！？！？！？我非常沮丧，我变得暴躁，所以我想我会把它留下一天; - ）
显示我们经常低估了多少努力使计算机做任何事情...甚至只画一条简单的线......它甚至不是曲线，更不用说大圆或横向mercator或任何花哨的...只是一个简单的bluddy线！？！？！？ ; - ）
非常感谢所有发帖的人！
再次干杯。基思。
6 个答案:
答案 0 :(得分：22)
计算向量AB
首先定义从A点（1，-1）到B点（2,4）的向量，从B中减去A. 矢量将是Vab（1,5）。
计算AB的长度
使用毕达哥拉斯定理计算向量AB的长度。
|Vab| = SQRT(1²+5²)
长度为（圆形）5.1
计算单位矢量
将矢量除以其长度以获得单位矢量（长度为1的矢量）。
V1(1/5.1,5/5.1) = V1(0.2, 0.98)
计算长度为4
的向量现在将V1乘以你想要的长度，例如4，得到Vt。
Vt(0.2*4,0.98*4) = Vt(0.8,3.92)
计算目标点
将向量Vt添加到A点以获得点T（目标）。
T = A + Vt = T(1.8,2.92)
编辑：回答您的修改
LengthOfHypotenuse方法看起来应该是
- 修正了计算bSq的错误
- 并删除了冗余的Math.Abs调用，因为2的pow为始终为正
- 删除了0.5的添加，不知道为什么你需要那个
-
你至少应该使用一个浮点作为返回值（双倍或小数也可以）
//You should work with Vector2 class instead of Point and use their Length property private double LengthOfHypotenuse(Point a, Point b) { double aSq = Math.Pow(a.X - b.X, 2); // horizontal length squared double bSq = Math.Pow(a.Y - b.Y, 2); // vertical length squared return Math.Sqrt(aSq + bSq); // length of the hypotenuse }
方法Draw（Point a，Point b）应如下所示：
-
更正了DrawCell（）调用
private void Draw(Point a, Point b) { double maxDistance = LengthOfHypotenuse(a, b); for (int distance = 0; distance < maxDistance; ++distance) { var point = CalculatePoint(new Vector2(a), new Vector2(b), distance); DrawCell(point.X, point.Y, _theLineBrush); } }
您的CalculatePoint（Point a，Point b，int distance）方法：
-
将一些计算移到Vector2类
private Point CalculatePoint(Vector2 a, Vector2 b, int distance) { Vector2 vectorAB = a - b; return a + vectorAB.UnitVector * distance; }
我已经扩展了Vector类，以便添加缺少的运算符（功能到AgentFire）
//AgentFire: Better approach (you can rename the struct if you need):
struct Vector2 {
public readonly double X;
public readonly double Y;
public Vector2(Point p) : this(p.X,p.Y) {
}
public Vector2(double x, double y) {
this.X = x;
this.Y = y;
}
public static Vector2 operator -(Vector2 a, Vector2 b) {
return new Vector2(b.X - a.X, b.Y - a.Y);
}
public static Vector2 operator +(Vector2 a, Vector2 b) {
return new Vector2(b.X + a.X, b.Y + a.Y);
}
public static Vector2 operator *(Vector2 a, double d) {
return new Vector2(a.X * d, a.Y * d);
}
public static Vector2 operator /(Vector2 a, double d) {
return new Vector2(a.X / d, a.Y / d);
}
public static implicit operator Point(Vector2 a) {
return new Point((int)a.X, (int)a.Y);
}
public Vector2 UnitVector {
get { return this / Length; }
}
public double Length {
get {
double aSq = Math.Pow(X, 2);
double bSq = Math.Pow(Y, 2);
return Math.Sqrt(aSq + bSq);
}
}
public override string ToString() {
return string.Format("[{0}, {1}]", X, Y);
}
}
答案 1 :(得分：6)
更好的方法（如果需要，可以重命名结构）：
struct Vector2
{
public readonly float X;
public readonly float Y;
public Vector2(float x, float y)
{
this.X = x;
this.Y = y;
}
public static Vector2 operator -(Vector2 a, Vector2 b)
{
return new Vector2(b.X - a.X, b.Y - a.Y);
}
public static Vector2 operator +(Vector2 a, Vector2 b)
{
return new Vector2(a.X + b.X, a.Y + b.Y);
}
public static Vector2 operator *(Vector2 a, float d)
{
return new Vector2(a.X * d, a.Y * d);
}
public override string ToString()
{
return string.Format("[{0}, {1}]", X, Y);
}
}
要获得中点，您只需执行(a - b) * d + a操作：
class Program
{
static void Main(string[] args)
{
Vector2 a = new Vector2(1, 1);
Vector2 b = new Vector2(3, 1);
float distance = 0.5f; // From 0.0 to 1.0.
Vector2 c = (a - b) * distance + a;
Console.WriteLine(c);
}
}
这会给你一点：
output:\> [2, 1]
之后您需要的是for(the distance; up to one ; d += step)从 0.0 到 1.0 并绘制像素。
答案 2 :(得分：4)
private static Point CalculatePoint(Point a, Point b, int distance)
{
// a. calculate the vector from o to g:
double vectorX = b.X - a.X;
double vectorY = b.Y - a.Y;
// b. calculate the proportion of hypotenuse
double factor = distance / Math.Sqrt(vectorX * vectorX + vectorY * vectorY);
// c. factor the lengths
vectorX *= factor;
vectorY *= factor;
// d. calculate and Draw the new vector,
return new Point((int)(a.X + vectorX), (int)(a.Y + vectorY));
}
答案 3 :(得分：2)
尝试删除X和Y表达式括号中的“幅度”项：
(int)( ((double)a.X + vectorX * distance) + 0.5 )
答案 4 :(得分：1)
private Point CalculatePoint(Point a, Point b, int distance) {
Point newPoint = new Point(10,10);
Double Magnitude = Math.Sqrt(Math.Pow((b.Y - a.Y),2) + Math.Pow((b.X - a.X),2));
newPoint.X = (int)(a.X + (distance * ((b.X - a.X)/magnitude)));
newPoint.Y = (int)(a.Y + (distance * ((b.Y - a.Y)/magnitude)));
return newPoint;
}
答案 5 :(得分：1)
好的伙计们，我发现了我的主要错误。这是一个经典的Doh！我的Draw方法是在p.X，p。 X 上绘画
所以，我终于得到了一些有用的东西。请注意，我并不是说这是一个“好的解决方案”，或“唯一可行的解决方案”我只是说它做了我想做的事情; - ）
这是我的更新工作代码:(这次完整且自包含; - ）
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Diagnostics;
namespace DrawLines
{
public class MainForm : Form
{
#region constants and readonly attributes
private const int CELL_SIZE = 4; // width and height of each "cell" in the bitmap.
private readonly Bitmap _myBitmap; // to draw on (displayed in picBox1).
private readonly Graphics _myGraphics; // to draw with.
// actual points on _theLineString are painted red.
private static readonly SolidBrush _thePointBrush = new SolidBrush(Color.Red);
// ... and are labeled in /*Bold*/ Black, 16 point Courier New
private static readonly SolidBrush _theLabelBrush = new SolidBrush(Color.Black);
private static readonly Font _theLabelFont = new Font("Courier New", 16); //, FontStyle.Bold);
// the interveening calculated cells on the lines between actaul points are painted Silver.
private static readonly SolidBrush _theLineBrush = new SolidBrush(Color.Silver);
// the points in my line-string.
private static readonly Point[] _thePoints = new Point[] {
// x, y c i
new Point(170, 85), // A 0
new Point( 85, 70), // B 1
new Point(209, 66), // C 2
new Point( 98, 120), // D 3
new Point(158, 19), // E 4
new Point( 2, 61), // F 5
new Point( 42, 177), // G 6
new Point(191, 146), // H 7
new Point( 25, 128), // I 8
new Point( 95, 24) // J 9
};
#endregion
public MainForm() {
InitializeComponent();
// initialise "the graphics system".
_myBitmap = new Bitmap(picBox1.Width, picBox1.Height);
_myGraphics = Graphics.FromImage(_myBitmap);
picBox1.Image = _myBitmap;
}
#region DrawPoints upon MainForm_Load
private void MainForm_Load(object sender, EventArgs e) {
DrawPoints();
}
// draws and labels each point in _theLineString
private void DrawPoints() {
char c = 'A'; // label text, as a char so we can increment it for each point.
foreach ( Point p in _thePoints ) {
DrawCell(p.X, p.Y, _thePointBrush);
DrawLabel(p.X, p.Y, c++);
}
}
#endregion
#region DrawLines on button click
// =====================================================================
// Here's the interesting bit. DrawLine was called Draw
// Draws a line from A to B, by using X-values to calculate the Y values.
private void DrawLine(Point a, Point b)
{
if ( a.Y > b.Y ) // A is below B
Swap(ref a, ref b); // make A the topmost point (ergo sort by Y)
Debug.Assert(a.Y < b.Y, "A is still below B!");
var left = Math.Min(a.X, b.X);
var right = Math.Max(a.X, b.X);
int width = right - left;
Debug.Assert(width >= 0, "width is negative!");
var top = a.Y;
var bottom = b.Y;
int height = bottom - top;
Debug.Assert(height >= 0, "height is negative!");
if ( width > height ) {
// use given X values to calculate the Y values,
// otherwise it "skips" some X's
double slope = (double)height / (double)width;
Debug.Assert(slope >= 0, "slope is negative!");
if (a.X <= b.X) // a is left-of b, so draw left-to-right.
for ( int x=1; x<width; ++x ) // xOffset
DrawCell( (left+x), (a.Y + ((int)(slope*x + 0.5))), _theLineBrush);
else // a is right-of b, so draw right-to-left.
for ( int x=1; x<width; ++x ) // xOffset
DrawCell( (right-x), (a.Y + ((int)(slope*x + 0.5))), _theLineBrush);
} else {
// use given Y values to calculate the X values,
// otherwise it "skips" some Y's
double slope = (double)width/ (double)height;
Debug.Assert(slope >= 0, "slope is negative!");
if (a.X <= b.X) { // a is left-of b, so draw left-to-right. (FG)
for ( int y=1; y<height; ++y ) // yOffset
DrawCell( (a.X + ((int)(slope*y + 0.5))), (top+y), _theLineBrush);
} else { // a is right-of b, so draw right-to-left. (DE,IJ)
for ( int y=1; y<height; ++y ) // yOffset
DrawCell( (b.X + ((int)(slope*y + 0.5))), (bottom-y), _theLineBrush);
}
}
}
private void btnDrawLines_Click(object sender, EventArgs e) {
DrawLines(); // join the points
DrawPoints(); // redraw the labels over the lines.
}
// Draws a line between each point in _theLineString.
private void DrawLines() {
int n = _thePoints.Length - 1; // one less line-segment than points
for ( int i=0; i<n; ++i )
DrawLine(_thePoints[i], _thePoints[i+1]);
picBox1.Invalidate(); // tell the graphics system that the picture box needs to be repainted.
}
private void Swap(ref Point a, ref Point b) {
Point tmp = a;
a = b;
b = tmp;
}
#endregion
#region actual drawing on _myGraphics
// there should be no calls to Draw or Fill outside of this region
private void DrawCell(int x, int y, Brush brush) {
_myGraphics.FillRectangle(
brush
, x*CELL_SIZE
, y*CELL_SIZE
, CELL_SIZE // width
, CELL_SIZE // heigth
);
}
private void DrawLabel(int x, int y, char c) {
string s = c.ToString();
_myGraphics.DrawString(
s, _theLabelFont, _theLabelBrush
, x * CELL_SIZE + 5 // x
, y * CELL_SIZE - 10 // y
);
}
#endregion
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent() {
this.picBox1 = new System.Windows.Forms.PictureBox();
this.btnDrawLines = new System.Windows.Forms.Button();
((System.ComponentModel.ISupportInitialize)(this.picBox1)).BeginInit();
this.SuspendLayout();
//
// picBox1
//
this.picBox1.Dock = System.Windows.Forms.DockStyle.Fill;
this.picBox1.Location = new System.Drawing.Point(0, 0);
this.picBox1.Name = "picBox1";
this.picBox1.Size = new System.Drawing.Size(1000, 719);
this.picBox1.TabIndex = 0;
this.picBox1.TabStop = false;
//
// btnDrawLines
//
this.btnDrawLines.Location = new System.Drawing.Point(23, 24);
this.btnDrawLines.Name = "btnDrawLines";
this.btnDrawLines.Size = new System.Drawing.Size(77, 23);
this.btnDrawLines.TabIndex = 1;
this.btnDrawLines.Text = "Draw Lines";
this.btnDrawLines.UseVisualStyleBackColor = true;
this.btnDrawLines.Click += new System.EventHandler(this.btnDrawLines_Click);
//
// MainForm
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(1000, 719);
this.Controls.Add(this.btnDrawLines);
this.Controls.Add(this.picBox1);
this.Location = new System.Drawing.Point(10, 10);
this.MinimumSize = new System.Drawing.Size(1016, 755);
this.Name = "MainForm";
this.SizeGripStyle = System.Windows.Forms.SizeGripStyle.Hide;
this.StartPosition = System.Windows.Forms.FormStartPosition.Manual;
this.Text = "Draw Lines on a Matrix.";
this.Load += new System.EventHandler(this.MainForm_Load);
((System.ComponentModel.ISupportInitialize)(this.picBox1)).EndInit();
this.ResumeLayout(false);
}
private System.Windows.Forms.PictureBox picBox1;
private System.Windows.Forms.Button btnDrawLines;
#endregion
}
}
编辑 - 更新上面的代码：此版本绘制“实线”。之前发布的版本在几乎垂直的行中跳过了单元格，所以在这些情况下我将算法反转以计算X值（而不是Y值）...现在我可以使用它来设置（并绘制）“实心栅栏”围绕“可导航区域”; - ）
这是正确结果的更新图片。
再次感谢给所有帮助过的人...并且你们提供了帮助; - ）
干杯。基思。
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